System and methods for locating and ablating arrhythomogenic tissues

ABSTRACT

A catheter for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region has a handle assembly, a shaft having a proximal end coupled to the handle assembly, a first expandable member provided at the distal end of the shaft, and a second expandable member positioned adjacent to, but spaced apart from, the first expandable member. The second expandable member has an ablation element that emits energy to a radially surrounding area to ablate tissue.

RELATED CASES

This is a continuation-in-part of co-pending Ser. No. 10/897,887,entitled “System and Method for Mapping and Ablating Body Tissue of theInterior Region of the Heart”, filed Jul. 22, 2004, now pending, whichis in turn a continuation-in-part of co-pending Ser. No. 10/744,354,entitled “System and Method for Mapping and Ablating Body Tissue of theInterior Region of the Heart”, filed Dec. 22, 2003, which is in turn acontinuation of Ser. No. 09/975,269, filed Oct. 11, 2001, now U.S. Pat.No. 6,671,533, whose disclosures are incorporated by this reference asthough fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to systems and methods for mapping andablating body tissue of the interior regions of the heart for treatingcardiac arrrhythmias.

2. Description of the Prior Art

Atrial fibrillation (AF) is a common cardiac arrhythmia associated withsignificant morbidity and mortality. A number of clinical conditions mayarise from irregular cardiac functions and the resulting hemodynamicabnormalities associated with AF, including stroke, heart failure andother thromboembolic events. AF is a significant cause of cerebralstroke, wherein the fibrillating motion in the left atrium induces theformation of thrombus. A thromboembolism is subsequently dislodged intothe left ventricle and enters the cerebral circulation where stroke mayresult.

For many years, the only curative treatment for AF has been surgical,with extensive atrial incisions used to compartmentalize the atrial massbelow that critical for perpetuating AF. Recently, transcatheter linearradiofrequency ablation in the right or left atrium has been used toreplicate surgical procedures in patients with paroxysmal or chronic AF.Such ablation is carried out by a catheter system that performs bothmapping and ablation. With current techniques, there is stilluncertainty regarding the number of lesions, the optimum ablation site,and the need for continuous lines. As a result, focal ablation has beenproposed as an alternative approach, due to the belief that ectopicbeats originating within or at the ostium of the pulmonary veins (PV)may be the source of paroxysmal and even persistent AF. Althoughsuccessful, the technical feasibility of this technique is restricted bythe difficulty in mapping the focus if the patient is in AF or has noconsistent firing, the frequent existence of multiple foci causing highrecurrence rates, and a high incidence of PV stenosis.

There are a number of drawbacks associated with the catheter-basedmapping and ablation systems that are currently known in the art. Oneserious drawback lies in the unstable positioning of the catheter insidethe atrium of the heart. When a catheter is not properly stabilized, themapping becomes difficult and inaccurate.

Another drawback is associated with certain catheter-based systems thatutilize an expandable balloon that is inflated to conform to thepulmonary vein ostium. After the balloon is inflated and the catheterpositioned, it becomes difficult to map or record the distal PVpotentials without removing this catheter and placing another mappingcatheter inside the PV. Moreover, inflation of the balloon to conform tothe pulmonary vein ostium blocks blood flow to the left atrium, and suchprolonged blockage can have adverse effects to the patient. Blockage ofblood flow from the PV deprives the patient from receiving oxygenatedblood. In addition, the blockage may be a potential source for stenosis.

Thus, there still remains a need for a catheter-based system and methodthat can effectively map and ablate potentials (also known as spikes)inside PVs which can induce paroxysmal AF, while avoiding the drawbacksset forth above.

SUMMARY OF THE DISCLOSURE

It is an objective of the present invention to provide a system andmethod that effectively maps or records distal PV potentials and ablatesthe PV ostium.

It is another objective of the present invention to provide a system andmethod that effectively maps and ablates potentials without blockingblood flow.

In order to accomplish the objects of the present invention, there isprovided a catheter for sensing electrical events about a selectedannulus region of the heart and for treating tissue in the selectedannulus region. The catheter has a handle assembly, a shaft having aproximal end coupled to the handle assembly, a first expandable memberprovided at the distal end of the shaft, and a second expandable memberpositioned adjacent to, but spaced apart from, the first expandablemember. The second expandable member has an ablation element that emitsenergy to a radially surrounding area to ablate tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a mapping and ablation system according to oneembodiment of the present invention.

FIG. 2 is a perspective view of the catheter of the system of FIG. 1.

FIG. 3 is an enlarged view of the distal tip section of the catheter ofFIGS. 1 and 2.

FIG. 4 is a cross-sectional view of the distal tip section of FIG. 3taken along lines A-A thereof.

FIG. 5 is a cross-sectional view of the distal tip section of FIG. 3taken along lines B-B thereof.

FIG. 6 illustrates how the catheter of FIGS. 1 and 2 is deployed for useinside the heart of a patient.

FIG. 7 is a cross-sectional view illustrating the catheter of FIGS. 1and 2 in use in a pulmonary vein during the mapping and ablation steps.

FIG. 8 illustrates the steering mechanism of the catheter of FIGS. 1 and2.

FIG. 9 illustrates a mapping and ablation system according to anotherembodiment of the present invention.

FIG. 10 is a perspective view of the catheter of the system of FIG. 9.

FIG. 11 is an enlarged view of the distal tip section of the catheter ofFIGS. 9 and 10.

FIG. 12 is a cross-sectional view of the distal tip section of FIG. 11taken along lines A-A thereof.

FIG. 13 is a cross-sectional view of the distal tip section of FIG. 11taken along lines B-B thereof.

FIG. 14 is an enlarged persepective view of the distal tip section ofthe catheter of FIGS. 9 and 10.

FIG. 15 illustrates a mapping and ablation system according to anotherembodiment of the present invention.

FIG. 16 is an enlarged persepective view of the distal tip section ofthe catheter of FIG. 15.

FIG. 17 illustrates an ablation system according to yet anotherembodiment of the present invention.

FIG. 18 is a perspective view of the catheter of the system of FIG. 17.

FIG. 19 is an enlarged view of the distal tip section of the catheter ofFIGS. 17 and 18.

FIG. 20 is a cross-sectional view of the distal tip section of FIG. 19taken along lines A-A thereof.

FIG. 21 is a cross-sectional view of the distal tip section of FIG. 19taken along lines B-B thereof.

FIG. 22 illustrates how the catheter of FIGS. 17 and 18 is deployed foruse inside the heart of a patient.

FIG. 23 is a cross-sectional view illustrating the catheter of FIGS. 17and 18 in use in a pulmonary vein.

FIG. 24 illustrates the steering mechanism of the catheter of FIGS. 17and 18.

FIG. 25 illustrates an ablation system according to yet a furtherembodiment of the present invention.

FIG. 26 is a perspective view of the catheter of the system of FIG. 25.

FIG. 27 is an enlarged view of the distal tip section of the catheter ofFIGS. 25 and 26.

FIG. 28 is a cross-sectional view of the distal tip section of FIG. 27taken along lines A-A thereof.

FIG. 29 is a cross-sectional view of the distal tip section of FIG. 27taken along lines B-B thereof.

FIG. 30 is an enlarged persepective view of the distal tip section ofthe catheter of FIGS. 25 and 26.

FIG. 31 illustrates a mapping and ablation system according to yetanother embodiment of the present invention.

FIG. 32 is an enlarged persepective view of the distal tip section ofthe catheter of FIG. 31.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplatedmodes of carrying out the invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of illustratinggeneral principles of embodiments of the invention. The scope of theinvention is best defined by the appended claims. In certain instances,detailed descriptions of well-known devices, compositions, components,mechanisms and methods are omitted so as to not obscure the descriptionof the present invention with unnecessary detail.

The present invention provides a catheter system that has two separateelements for performing the mapping and ablation operations. A firstelement that includes ring electrodes is provided along a distal ringand functions to map the region of the heart that is to be treated.After the mapping has been completed, a second element that includes atransducer mounted inside a balloon is positioned at the location whereablation is to be performed, and is used to ablate the selected tissue.During the ablation, the distal ring functions to anchor the position ofthe balloon, while the balloon is inflated to a maximum diameter that isless than the diameter of the distal ring and the annulus where thetreatment is taking place. As a result, blood can still flow unimpededthrough the annulus.

Even though the present invention will be described hereinafter inconnection with treating AF, it is understood that the principles of thepresent invention are not so limited, but can be used in otherapplications (e.g., treatment of accessory pathways, atrial flutter,ventricular tachycardia), and in other body pathways (e.g., rightatrium, superior vena cava, right ventricle, left ventricle).

FIGS. 1-8 illustrate a catheter system 20 according to one embodiment ofthe present invention. The catheter system 20 has a tubular shaft 22having a distal tip section 24, a distal end 26, a proximal end 28, andat least one lumen 30 extending through the shaft 22. A handle assembly32 is attached to the proximal end 28 of the shaft 22 using techniquesthat are well-known in the catheter art.

The distal tip section 24 includes an expandable balloon 38 and a distalring 80 that makes up the distal-most end of the shaft 22. A transducer60 (e.g., piezoelectric or ultrasound) is housed inside the balloon 38.The balloon 38 can be made from any conventional material (such as butnot limited to silicone, polyurethane, latex, polyamide andpolyethylene), and heat bonded or otherwise attached to the shaft 22using techniques that are well-known in the catheter art.

The distal ring 80 can be preformed into a generally curved or circularshape, resembling an open loop. The shape of the distal ring 80corresponds to the circumferential geometry of a selected annulus (e.g.,the PV) in the heart. In fact, the preformed shape of the distal ring 80can be provided in a variety of curved geometries to overlie theanatomical geometry of the selected annulus. The distal ring 80 includesa transition section 82 that extends distally at an angle from thelongitudinal axis of the shaft 22, and has a generally open-loopedcircular section 84 that extends from the transition section 82. As bestseen from FIG. 3, the circular section 84 is oriented at anapproximately perpendicular orientation from the longitudinalorientation of the shaft 22. The distal ring 80 can be made from thesame material as the shaft 22. Such a material can be an electricallynonconductive, biocompatible, resilient plastic material which retainsits shape and which does not soften significantly at human bodytemperature (e.g., Pebax™, polyethylene or polyester). As a non-limitingexample, the geometry of the distal ring 80 can be created bythermoforming it into the desired shape.

A plurality of thermocouple wires 54 can have their distal tips securedto the interior surface of the balloon 38 (see FIG. 3), and are used todetect the temperature at the treatment site.

A plurality of ring electrodes 58 are provided in spaced-apart mannerabout the circular section 84 of the distal ring 80. The ring electrodes58 can be made of a solid, electrically conducting material, likeplatinum or gold, that is attached about the circular section 84.Alternatively, the ring electrodes 58 can be formed by coating theexterior surface of the circular section 84 with an electricallyconducting material, such as platinum or gold. The coating can beapplied by sputtering, ion beam deposition or similar known techniques.The number of ring electrodes 58 can vary depending on the particulargeometry of the region of use and the functionality desired.

As will be explained in greater detail below, the ring electrodes 58function to map the region of the heart that is to be treated. After themapping has been completed, the balloon 38 is positioned at the locationwhere ablation is to be performed, and the distal ring 80 functions toanchor the position of the balloon 38. The balloon 38 is expanded, buteven the greatest expanded diameter of the balloon 38 will be providedto be less than the diameter of the distal ring 80 when the distal ring80 is fully deployed (see FIGS. 2, 3 and 7). The ablation is thencarried out by energy that is emitted from the ultrasound transducer 60through the inflation media (e.g., fluid, saline, contrast media ormixture) inside the balloon 38, and the balloon 38 itself.

A standard Luer fitting 34 is connected to the proximal end 36 of thehandle assembly 32 using techniques that are well-known in the catheterart. The Luer fitting 34 provides a fluid line for inflation media to beintroduced to inflate the balloon 38 at the distal tip section 24 of theshaft 22. The inflation media is delivered via an inflation lumen 76that extends from the handle assembly 32 (and coupled to the line 78 ofthe Luer fitting 34), and terminates at the balloon 38.

A connector assembly 40 is also connected to the proximal end 36 of thehandle assembly 32 using techniques that are well-known in the catheterart. The connector assembly 40 has a proximal connector 42 that couplesthe handle assembly 32 to the connector 44 of a control line 46 thatleads to an ultrasound generator 52. An EKG monitor 50 is coupled to theultrasound generator 52 via another line 48. The EKG monitor 50 can be aconventional EKG monitor which receives (via the ultrasound generator52) electrical signals detected by the ring electrodes 58 at the distaltip section 24, and processes and displays these electrical signals toassist the physician in locating the site of potentials in a PV. Theultrasound generator 52 can be a conventional ultrasound generator thatcreates and transmits ablating energy to the ultrasound transducer 60that is positioned inside the balloon 38. The ultrasound transducer 60will emit the energy to ablate the tissue that extends radially from theposition of the balloon 38.

Electrical wires (not shown) extend from the ultrasound generator 52along the lines 46 and 48, and conductor wires 62 and ultrasound wires63 extend through the connector assembly 40, the handle assembly 32 andthe lumen 30 of the shaft 22 to the distal tip section 24 of the shaft22 to couple the ring electrodes 58 and the transducer 60, respectively.In addition, the thermocouple wires 54 can extend from the balloon 38through the lumen 30 of the shaft 22 and the handle assembly 32 to theproximal connector 42, where they can be electrically coupled by thewires in the line 46 to the ultrasound generator 52 where thetemperature can be displayed.

The handle assembly 32 also includes a steering mechanism 70 thatfunctions to deflect the distal tip section 24 of the shaft 22 formaneuvering and positioning the distal tip section 24 at the desiredlocation in the heart. Referring to FIGS. 1, 5 and 8, the steeringmechanism 70 includes a steering wire 72 that extends in the main lumen30 of the shaft 22 from its proximal end at the handle assembly 32 toits distal end which terminates in the distal tip section 24 before thelocation of the balloon 38. The proximal end of the steering wire 72 iswound around or secured to an anchor 77 that is fixedly positionedinside the handle assembly 32. The steering mechanism 70 also includes aflat wire 75 that extends in the lumen 30 from the anchor 77 to itsdistal end at a location slightly proximal to the balloon 38 (as shownin FIG. 5). The flat wire 75 is attached to the steering wire 72 at thedistal ends of the flat wire 75 and the steering wire 72 so as to becontrolled by the steering wire 72. Specifically, by pushing thesteering mechanism 70 forward in a distal direction, the steeringmechanism 70 will pull the steering wire 72 in a proximal direction,causing the distal tip section 24 to deflect to one direction (see inphantom in FIG. 8). By pulling back the steering mechanism 70 in aproximal direction, the steering wire 72 is deactivated and the distaltip section 24 returns to its neutral position or deflects to theopposite direction.

The distal ring 80 can be preformed to a fixed size (i.e., diameter) andshape that cannot be changed. Alternatively, the diameter of the distalring 80 can be adjusted using techniques and incorporating mechanismsthat are well-known in the catheter art.

FIGS. 6 and 7 illustrate how the catheter system 20 is used. First, aguide sheath 88 is provided to deliver the shaft 22 and distal ring 80to the desired location (e.g., the left atrium) in the heart. The shaft22 is slid into the hollow lumen of the guide sheath 88, and the guidesheath 88 can slide forward and backward along the longitudinal axis ofthe shaft 22. When the guide sheath 88 is slid forwardly towards thedistal ring 80, the distal ring 40 is progressively straightened out anddrawn into the lumen of the guide sheath 88. Thus, when confined withthe guide sheath 88, the distal ring 80 assumes the generally linear lowprofile shape of the guide sheath 88, which allows a physician to employconventional percutaneous access techniques to introduce the catheter 20into a selected region of the heart through a vein or artery. When theguide sheath 88 is slid rearwardly away from the distal ring 80, thedistal ring 80 is uncovered and its resilient memory will cause thedistal ring 80 to re-assume its preformed generally circular shape.

To introduce and deploy the distal tip section 24 within the heart, thephysician uses a conventional introducer to establish access to aselected artery or vein. With the guide sheath 88 confining the distalring 80, and with the balloon 38 deflated, the physician introduces theshaft 22 and the guide sheath 88 through a conventional hemostatic valveon the introducer and progressively advances the guide sheath 88 throughthe access vein or artery into the desired atrium, such as the leftatrium as shown in FIG. 6. The physician observes the progress of theguide sheath 88 using fluoroscopic or ultrasound imaging. The guidesheath 88 can include a radio-opaque compound, such as barium, for thispurpose. Alternatively, radio-opaque markers can be placed at the distalend of the guide sheath 88.

The shaft 22 and the guide sheath 88 can be maneuvered to the leftatrium by the steering mechanism 70. Once located in the left atrium,the physician slides the guide sheath 88 back to free the distal ring 80which resiliently returns to its preformed shape. The distal ring 80 isthen maneuvered into contact with the selected annulus (e.g., theostium) with the aid of fluoroscopy. Good contact is established whenthe ring electrodes 58 contact the selected annulus, and at this time,the physician operates a control located on the ultrasound generator 52to effectuate the mapping of the selected annulus by the ring electrodes58. The results of the mapping operation are processed and displayed atthe EKG monitor 50. A differential input amplifier (not shown) in theEKG monitor 50 processes the electrical signals received from the ringelectrodes 58 via the wires 62, and converts them to graphic images thatcan be displayed. The thermocouple wires 54 can also function to monitorthe temperature of the surrounding tissue, and provide temperatureinformation to the ultrasound generator 52. Throughout this mappingoperation, the balloon 38 remains deflated.

Once the mapping operation has been completed and the desired positionof the balloon 38 has been confirmed, the physician can then inflate theballoon 38 using inflation media. The balloon 38 is preferablymanufactured using known techniques to a predetermined diameter so thatits diameter at its maximum expansion will be less than the diameter ofthe distal ring 80 and the annulus or vessel (e.g., the PV in FIG. 7)where the ablation is to take place. The physician then controls theultrasound generator 52 to generate ultrasound energy that is propagatedthrough the wires 63 to the ultrasound transducer 60 that is positionedinside the balloon 38. The energy radiates in a radial manner from thetransducer 60, propagates through the inflation media (which acts as anenergy transmitting medium) inside the balloon 38, exits the balloon 38and then reaches the selected tissue (typically in a waveform) to ablatethe tissue. See the arrows E in FIG. 7 which illustrate the radiation ofthe energy from the transducer 60.

During the ablation, the distal ring 80 functions to anchor the distaltip section 24 inside the PV at the desired location so that theablation can be performed accurately. In contrast to known cathetersystems where the same element is used to anchor and ablate, byproviding a separate element (i.e., the distal ring 80) to anchor thedistal tip section 24, the function of the ablation element (i.e., theballoon 38 and transducer 60) will not be affected by the anchoringdevice, thereby ensuring that the ablation is performed accurately andeffectively. In addition, since the maximum diameter of the balloon 38is always smaller than the smallest diameter of the distal ring 80,blood will be able flow through the distal ring 80 and around thesurfaces of the balloon 38.

When the ablation has been completed, the balloon 38 is deflated and thedistal tip section 24 withdrawn from the heart.

FIGS. 9-14 illustrate modifications made to the catheter system 20 ofFIGS. 1-5 to allow contrast medium to be introduced while the catheteris located within the vessel ostium and while the balloon 38 isinflated. The catheter system 20a in FIGS. 9-14 essentially provides anadditional tubing and lumen to facilitate the injection of the contrastmedium. The catheter system 20 in FIGS. 1-5 did not provide anadditional lumen, so the contrast medium for vessel geometry andcatheter location could not be readily verified. Hence, the cathetersystem 20 a makes it easier to verify vessel geometry and catheterlocation since the blood flow from within the vessel will not wash outwhen the contrast medium is injected due to balloon inflation.

Since the catheter system 20 a merely includes modifications to thecatheter system 20, the descriptions relating to the same elements andtheir functions will not be repeated herein. Instead, the same numeralsused to designate elements in FIGS. 1-5 will be used to designate thesame elements in FIGS. 9-14, except that an “a” will be added to thedesignations in FIGS. 9-14.

The catheter system 20 a provides an additional tubing 100 that extendsfrom the handle assembly 32 a (see FIGS. 9-10). This tubing 100 isconnected to a lumen 102 that extends through the shaft 22 a, thetransducer 60 a inside the balloon 38 a, and exits at the distal-mostend of the shaft 22 a. See FIGS. 11 and 14. The contrast medium can beinjected via the tubing 100 and the lumen 102 by a syringe (not shown),and exits the catheter into the blood vessel at the location of thedistal ring 80 a to provide visibility of the location of the distalring 80 a and the balloon 38 a. A guidewire (not shown) can be insertedinto this lumen 102 to increase the mobility of the shaft 22 a intobranches of the main vessel.

In addition, the flat wire 75 a extends in the lumen 30 a from thedistal section of the shaft 22 a (not shown in FIGS. 9-14).

FIGS. 15-16 illustrate yet another modification that can be made to thesystem 20 in FIGS. 1-5. The catheter system 20 b in FIGS. 15-16 iscomprised of two separate catheters, a first catheter 120 that carriesthe balloon 38 b and the transducer 60 b, and a second catheter 122 thatcarries the distal ring 80 b.

Since the catheter system 20 b merely includes modifications to thecatheter system 20 a, the descriptions relating to the same elements andtheir functions will not be repeated herein. Instead, the same numeralsused to designate elements in FIGS. 9-14 will be used to designate thesame elements in FIGS. 15-16, except that a “b” or a “c” will be addedto the designations in FIGS. 15-16. The only notable differences are (i)the catheter 120 has the same structure as the catheter 20 a with theexception of the distal ring 80a, and (ii) the catheter 122 has the samestructure as the catheter 120 except for the balloon 38 a, thetransducer 60 a, and the thermocouples.

The distal ring 80 b and the shaft 22 c of the catheter 122 can beinserted through the lumen 102 b of the catheter 120. In this regard,the distal ring 80 b can progressively straightened out and drawn intothe lumen 102 b of the catheter 120. Thus, when confined within thecatheter 120, the distal ring 80 b assumes the generally linear lowprofile shape of the catheter 120. When the distal ring 80 b exits thedistal-most end 124 of the catheter 120 (see FIG. 16), the distal ring80 b is uncovered and its shape memory (e.g., Nitinol) will cause thedistal ring 80 b to re-assume its preformed generally circular shape.

The catheter 122 can also be steered so that the diameter of the distalring 80 b can be varied. This can be accomplished by providing a pullingwire (not shown, but can be the same as 72 or 72 a), and then pullingthe pulling wire. The catheter 120 can also be steered so that thedistal end 124 can be deflected. The steering of the catheters 120, 122can be accomplished using steering mechanisms 70 b, 70 c that can be thesame as the steering mechanism 70 described in FIGS. 1-5.

The main lumen 30 b of the catheter 120 can be used to accomodate aguidewire (not shown), and can also be used for delivering contrastmedium. Therefore, the catheter system 20 b does not require anadditional tubing (such as 100) or lumen (such as 102) as in thecatheter system 20 a, although it is also possible to provide anadditional tubing (such as 100) or lumen (such as 102) if such isdesired.

The following illustrates one example of a possible use of the cathetersystem 20 b. A transseptal sheath (with a dilator in the sheath lumen)is typically inserted into the patient's femoral vein and placed intothe right atrium. Using a transseptal (Brockenbrough) needle, a punctureis produced in the fossa ovalis in the septal wall to provide accessfrom the right atrium to the left atrium. The sheath is then broughtinside the left atrium, the needle removed, and a guidewire is insertedthrough the lumen of the dilator to the target pulmonary vein or itsbranches. The distal opening of the dilator inside the sheath followsthe guidewire to the pulmonary vein. When the catheter 20 a is used, thedilator and the guidewire are removed and the catheter is inserted intothe transseptal sheath into the pulmonary vein. When the catheter 120 isused, only the dilator is removed and the lumen 102 b of the distal endof the catheter follows the path of the guidewire and into the targetPV. Once the catheter 20 a or 120 is situated in the pulmonary veinostium, the balloon 38 a or 38 b is inflated until it engages the ostialwall. Contrast media is injected in the lumen 102 or 102 b to visuallyverify the location of the transducer 60 a with respect to the pulmonaryvein anatomy.

For the catheter 20 a, the location of the transducer 60 a can beverified via contrast medium injection while the distal ring 80 arecords the PV potentials. This has not been possible with theconventional systems.

For the catheter system 20 b, the catheter 122 is inserted through thetubing 100 b and the distal ring 80 b exits from the lumen 102 b. Thediameter of the distal ring 80 b can be adjusted to fit the differentsizes of the pulmonary vein. The electrodes 58 b are again used to pickup the PV potentials. Once the potentials (or intracardiac signals) arerecorded, the catheter 122 can be removed, and if needed, contrastmedium can be injected for locating the transducer. Energy can then bedelivered to perform the ablation, as described above.

FIGS. 17-24 illustrate a catheter system 20 d according to yet anotherembodiment of the present invention. The catheter system 20 d is similarto the catheter system 20 in FIGS. 1-8, except that the catheter system20 d has a second balloon 37 d instead of a distal ring. As a result,the descriptions relating to the same elements and their functions inFIGS. 1-8 and FIGS. 17-24 will not be repeated herein. Instead, the samenumerals used to designate elements in FIGS. 1-8 will be used todesignate the same elements in FIGS. 17-24, except that a “d” will beadded to the designations in FIGS. 17-24.

The distal tip section 24 d includes a first expandable balloon 38 dthat can be the same as the balloon 38, and a second expandable balloon37 d. The balloons 37 d and 38 d can be positioned side-by-side next toeach other. A transducer 60 d (e.g., piezoelectric or ultrasound) isalso housed inside the first balloon 38 d. Both balloons 37 d and 38 dcan be made from any conventional material (such as but not limited tosilicone, polyurethane, latex, polyamide and polyethylene), and heatbonded or otherwise attached to the shaft 22 d using techniques that arewell-known in the catheter art. A plurality of thermocouple wires 54 dcan have their distal ends secured to the interior surface of the firstballoon 38 d (see FIG. 19), and are used to detect the temperature atthe treatment site.

Standard Luer fittings 34 d and 35 d are connected to the proximal end36 d of the handle assembly 32 d using techniques that are well-known inthe catheter art. The Luer fittings 34 d and 35 d provide fluid linesfor inflation media to be introduced to inflate the balloons 37 d and 38d at the distal tip section 24 d of the shaft 22 d. For example, theinflation media is delivered via an inflation lumen 76 d (see FIG. 21)that extends from the handle assembly 32 d (and coupled to the line 78 dof the Luer fitting 34 d), and terminates at the balloon 38 d.Similarly, the inflation media is delivered via an inflation lumen 73 dthat extends from the handle assembly 32 d (and coupled to the line 79 dof the Luer fitting 35 d), and terminates at the balloon 37d.

The connector assembly 40 d and its connection to the ultrasoundgenerator 52 d can be the same as described in FIGS. 1-8 above. Inaddition, the steering mechanism 70 d can also be the same as describedin FIGS. 1-8 above, except that the steering wire 72 d extends in themain lumen 30 d of the shaft 22 d from its proximal end at the handleassembly 32 d to its distal end which terminates in the distal tipsection 24 d before the location of the balloon 38 d.

FIGS. 22 and 23 illustrate how the catheter system 20 d is used. Theprimary difference between the operation of the catheter systems 20 and20 d is that mapping is not provided in the catheter system 20 d becausethere is no distal ring, and therefore no ring electrodes. First, atransseptal sheath 88 d is provided to deliver the shaft 22 d and theballoon 37 d to the desired location (e.g., the left atrium) in theheart. The shaft 22 d is slid into the hollow lumen of the sheath 88 d,and the sheath 88 d can slide forward and backward along thelongitudinal axis of the shaft 22 d.

To introduce and deploy the distal tip section 24 d within the heart,the physician uses a conventional introducer to establish access to aselected artery or vein. With the balloons 37 d and 38 d deflated, thephysician introduces the shaft 22 d and the transseptal sheath 88 d andprogressively advances the sheath 88 d through the access vein or arteryinto the desired atrium, such as the left atrium via standardtransceptal as shown in FIG. 22. The physician observes the progress ofthe sheath 88 d using fluoroscopic or ultrasound imaging. The sheath 88d can include a radio-opaque compound, such as barium, for this purpose.Alternatively, radio-opaque markers can be placed at the distal end ofthe sheath 88 d.

The shaft 22 d and the sheath 88 d can be maneuvered to the left atriumby the steering mechanism 70 d. See FIG. 23. Once located in the leftatrium, the physician slides the sheath 88 d back to expose the balloons37 d and 38 d. The balloon 37 d is then maneuvered and then expandedinto contact with the selected annulus (e.g., the ostium) with the aidof fluoroscopy.

Once the positioning operation has been completed and the desiredposition of the balloon 38 d has been confirmed, the physician can theninflate the balloon 38 d using inflation media. The balloon 38 d can bemanufactured using known techniques to a predetermined diameter so thatits diameter at its maximum expansion will be greater than the diameterof the other balloon 37 d and the annulus or vessel where the ablationis to take place. This allows the smaller-diameter balloon 37 d tosnugly contact and anchor a smaller-diameter vessel (e.g., the ostium inFIG. 23) while ablation is being performed in a larger-diameter vessel.The thermocouple wires 54 d can also function to monitor the temperatureof the surrounding tissue, and provide temperature information to theultrasound generator 52 d. The physician then controls the ultrasoundgenerator 52 d to generate ultrasound energy that is propagated throughthe wires 63 d to the ultrasound transducer 60 d that is positionedinside the balloon 38 d. The energy radiates in a radial manner from thetransducer 60 d, propagates through the inflation media (which acts asan energy transmitting medium) inside the balloon 38 d, exits theballoon 38 d and then reaches the selected tissue (typically in awaveform) to ablate the tissue. See the arrows E in FIG. 23 whichillustrate the radiation of the energy from the transducer 60 d.

Thus, during the ablation, the balloon 37 d functions to anchor thedistal tip section 24 d inside the PV at the desired location so thatthe ablation can be performed accurately. In contrast to known cathetersystems where the same element is used to anchor and ablate, byproviding a separate element (i.e., the balloon 37 d) to anchor thedistal tip section 24 d, the function of the ablation element (i.e., theballoon 38 d and transducer 60 d) will not be affected by the anchoringdevice, thereby ensuring that the ablation is performed accurately andeffectively.

When the ablation has been completed, the balloon 38 d is deflated andthe distal tip section 24 d withdrawn from the heart.

FIGS. 25-30 illustrate modifications made to the catheter system 20 d ofFIGS. 17-24 to allow contrast medium to be introduced while the catheteris located within the vessel ostium and the balloon 38 d inflated. Thecatheter system 20 e in FIGS. 25-30 essentially provides an additionaltubing and lumen to facilitate the injection of the contrast medium. Thecatheter system 20 d in FIGS. 17-24 did not provide an additional lumen,so the contrast medium for vessel geometry and catheter location couldnot be readily verified. Hence, the catheter system 20 e makes it easierto verify vessel geometry and catheter location since the blood flowfrom within the vessel will not wash out when the contrast medium isinjected due to balloon inflation.

Since the catheter system 20 e merely includes modifications to thecatheter system 20 d, the descriptions relating to the same elements andtheir functions will not be repeated herein. Instead, the same numeralsused to designate elements in FIGS. 17-24 will be used to designate thesame elements in FIGS. 25-30, except that an “e” will be added to thedesignations in FIGS. 25-30.

The catheter system 20 e provides an additional tubing 100 e thatextends from the handle assembly 32 e (see FIGS. 25-26). This tubing 100e is connected to a lumen 102 e that extends through the shaft 22 e, thetransducer 60 e inside the second balloon 38 e, and exits at thedistal-most end of the shaft 22 e. See FIGS. 27 and 30. The contrastmedium can be injected via the tubing 100 e and the lumen 102 e by asyringe (not shown), and exits the catheter into the blood vessel at thelocation of the balloon 37 e to provide visibility of the location ofthe balloons 37 e and 38 e. A guidewire (not shown) can be inserted intothis lumen 102 e to increase the mobility of the shaft 22 e intobranches of the main vessel.

In addition, the flat wire 75 e extends in the lumen 30 e from thedistal section of the shaft 22 e (not shown in FIGS. 25-30).

FIGS. 31-32 illustrate yet another modification that can be made to thesystem 20 d in FIGS. 17-24. The catheter system 20 f in FIGS. 31-32 iscomprised of two separate catheters, a first catheter 20 e that isidentical to the catheter 20 e in FIGS. 25-30 above, and a secondcatheter 122 that is identical to the catheter 122 in FIGS. 15 and 16.

The distal ring 80 b and the shaft 22 c of the catheter 122 can beinserted through the lumen 102 e of the catheter 20 e. In this regard,the distal ring 80 b can be progressively straightened out and drawninto the lumen 102 e of the catheter 20 e. Thus, when confined with thecatheter 20 e, the distal ring 80 b assumes the generally linear lowprofile shape of the catheter 20 e. When the distal ring 80 b exits thedistal-most end 124 e of the catheter 20 e (see FIG. 32), the distalring 80 b is uncovered and its shape memory (e.g., Nitinol) will causethe distal ring 80 b to re-assume its preformed generally circularshape.

The catheter 122 can also be steered so that the diameter of the distalring 80 b can be varied. This can be accomplished by providing a pullingwire (not shown, but can be the same as 72 or 72 a), and then pullingthe pulling wire. The catheter 20 e can also be steered so that thedistal end 124 e can be deflected.

The following illustrates one example of a possible use of the cathetersystem 20 f. A transseptal sheath (with a dilator in the sheath lumen)is typically inserted into the patient's femoral vein and placed intothe right atrium. Using a transseptal (Brockenbrough) needle, a punctureis produced in the fossa ovalis in the septal wall to provide accessfrom the right atrium to the left atrium. The sheath is then broughtinside the left atrium, the needle removed, and a guidewire is insertedthrough the lumen of the dilator to the target pulmonary vein or itsbranches. The distal opening of the dilator inside the sheath followsthe guidewire to the pulmonary vein. When the catheter 20 e is used,only the dilator is removed and the lumen 102 e of the distal end of thecatheter follows the path of the guidewire and into the target PV. Oncethe catheter 20 e is situated in the pulmonary vein ostium, the balloon38 e is inflated until it engages the ostial wall. Contrast media isinjected in the lumen 102 e to visually verify the location of thetransducer 60 e with respect to the pulmonary vein anatomy.

For the catheter 20 e, the location of the transducer 60 e can beverified via contrast medium injection while the distal ring 80 erecords the PV potentials. This has not been possible with theconventional systems.

For the catheter system 20 f, the catheter 122 is inserted through thetubing 100 e and the distal ring 80 b exits from the lumen 102 e. Thediameter of the distal ring 80 b can be adjusted to fit the differentsizes of the pulmonary vein. The electrodes 58 b are again used to pickup the PV potentials. Once the potentials (or intracardiac signals) arerecorded, the catheter 122 can be removed, and if needed, contrastmedium can be injected for locating the transducer. Energy can then bedelivered to perform the ablation, as described above.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

1. A catheter for sensing electrical events about a selected annulusregion of the heart and for treating tissue in the selected annulusregion, comprising: a handle assembly; a shaft having a proximal endcoupled to the handle assembly, and a distal end, the shaft extendingalong an axis; a first expandable member provided at the distal end; asecond expandable member positioned adjacent to, but spaced apart from,the first expandable member, the second expandable member having anablation element; and means for providing ablation energy to theablation element.
 2. The catheter of claim 1, wherein the ablationelement emits energy to a radially surrounding area.
 3. The catheter ofclaim 1, wherein the second expandable member covers the ablationelement.
 4. The catheter of claim 3, wherein the second expandablemember defines an interior space that is filled with a fluid.
 5. Thecatheter of claim 2, wherein the shaft has a main lumen, and furtherincluding a plurality of wires that are coupled to the ablation elementand extending through the main lumen.
 6. The catheter of claim 1,wherein the shaft has a main lumen, and the catheter further includes asteering mechanism that includes a steering wire extending through themain lumen to the distal end.
 7. The catheter of claim 1, wherein theshaft has a main lumen, and further including a plurality ofthermocouple wires that are coupled to the distal end and extendingthrough the main lumen.
 8. The catheter of claim 1, wherein theexpandable members are positioned side-by-side next to each other. 9.The catheter of claim 1, further including an energy source coupled tothe ablation element.
 10. The catheter of claim 1, further includingmeans for introducing contrast medium to the distal end of the shaft.11. The catheter of claim 1, further including: a contrast media tubingcoupled to the handle assembly; and a contrast media lumen extendingthrough the shaft and out the distal end of the shaft, the contrastmedia lumen coupled to the contrast media tubing.
 12. The catheter ofclaim 1, wherein the maximum diameter of the second expandable member isgreater than the maximum diameter of the first expandable member.
 13. Amethod of ablating tissue in a body cavity, comprising: providing acatheter having a shaft having a proximal end and a distal end, with thedistal end of the shaft having an anchoring element and an ablationelement that is separate from the mapping element; positioning theanchoring element at the desired treatment location in the body cavity,including injecting contrast medium to the distal end of the catheter;and actuating the ablation element to ablate the desired treatmentlocation.
 14. The method of claim 13, wherein the step of providing acatheter includes: providing the anchoring element in the form of afirst expandable member; and providing the ablation element in the formof a transducer housed inside a different second expandable member. 15.The method of claim 14, further including: providing the secondexpandable member with a maximum diameter that is greater than themaximum diameter of the first expandable member.
 16. The method of claim13, wherein the step of ablating the desired treatment location includesemitting energy to the desired treatment location.
 17. A system forsensing electrical events about a selected annulus region of the heartand for treating tissue in the selected annulus region, comprising: (a)a first catheter having: a handle assembly; a shaft having a proximalend coupled to the handle assembly, and a distal end, the shaftextending along an axis; an ablation element provided adjacent thedistal end of the shaft; and an expandable member provided next to theablation element; (b) a second catheter having: a handle assembly; ashaft having a proximal end coupled to the handle assembly of the secondcatheter, and a distal end, the shaft of the second catheter extendingalong an axis; and a distal ring provided at the distal end of the shaftof the second catheter and oriented perpendicular to the axis of theshaft of the second catheter, the distal ring having a plurality ofelectrodes positioned in spaced-apart manner about the distal ring ofthe second catheter; (c) an energy source coupled to the ablationelement; and (d) means coupled to the plurality of electrodes forprocessing electrical signals received from the plurality of electrodes.18. The system of claim 17, wherein: the expandable member is a firstexpandable member; and the ablation element is a transducer housedinside a different second expandable member that is positioned proximalof the first expandable element.
 19. A catheter for sensing electricalevents about a selected annulus region of the heart and for treatingtissue in the selected annulus region, comprising: a handle assembly; ashaft having a proximal end coupled to the handle assembly, and a distalend, the shaft extending along an axis; a first expandable memberprovided at the distal end; a second expandable member positionedadjacent to, but spaced apart from, the first expandable member, thesecond expandable member having an ablation element; and means forintroducing a guidewire to the distal end.
 20. The catheter of claim 19,further including: means for providing ablation energy to the ablationelement.